1. Field of the Invention
The present invention relates to apparatus and methods for connecting and repairing severed and separated nerve tissue. In particular, the present invention is directed to an apparatus and method for bringing together and joining the ends or stumps of nerve tissue where the nerve tissue has been severed, with the served ends of the nerve tissue spaced or gapped.
2. Prior Art
The repair of severed and/or broken nerve tissue has been addressed in the prior art. U.S. Pat. No. 3,786,817, issued to Palma teaches the joining of the ends of severed nerve tissue by inserting the severed ends in opposite ends of a tube so that the ends of the nerve tissue may be joined and begin growing together or regenerating. An opening in the tube provides for injection of matter for generating a environment conducive to nerve regeneration. After the nerve tissue ends have rejoined, the tube is removed from around the nerve junction by rupturing the tube.
The apparatus disclosed in this patent has several disadvantages. It is known that when nerve tissue is separated by a blow or striking force some of the nerve tissue adjacent the separated ends is damaged or destroyed, leaving a gap or spacing between the ends of the tissue. This gap or spacing between the ends of the severed nerve tissue must be overcome by lengthening the nerve tissue before the nerve ends can be physically joined, and the '817 patent does not address this problem. Another disadvantage is that after the nerve tissue has been lengthened the nerve tissue ends must be inserted in opposite ends of a tube and the person inserting the nerve ends into the tube does not have visual contact with the nerve ends when the ends are inside the tube. Without visual contact with the nerve ends, it is difficult to determine when the nerve ends are physically rejoined inside the tube. The teaching does not allow for the suturing of the nerve tissue ends, the nerve tissue ends are left to just grow together at will. Approximation, i.e., suturing, the nerve ends together more positively aligns the tissue and promotes healing of the severed tissue. Another problem inherent in this teaching is that the tube into which the nerve ends are inserted must be removed from around the nerve after regeneration of the nerve tissue occurs. Removal of the tube requires that the flesh be opened and that the tube be removed from around the nerve tissue. Palma overcomes this last problem in his U.S. Pat. No. 3,833,002 in which he discloses the use of a tubing made from a slow-dissolving material. However, the '002 patent fails to address other problems in the '817 patent.
The problem of visual contact with the ends of separated nerve tissue is addressed by de Medinaceli in his U.S. Pat. No. 4,586,504. This patent discloses a foldable sheet which is pre-marked, on which the nerve stumps are positioned while the sheet is open, according visual contact with the nerve tissue ends. The problem in the '504 patent is that this teaching does not address the problem of nerve end gap or spacing.
U.S. Pat. No. 4,662,884 issued to Stensaas, et al, discloses a nerve prostheses for promoting nerve tissue regeneration where there is no gap or very little gap between the severed nerve ends and suggests nerve tissue graft where the gap between nerve ends is 1 to 2 centimeters, or more. The severed nerve ends are brought together and held inside a tubular prostheses. However, after rejoining of the nerve tissue ends occurs, the tubular prostheses must be removed from around the nerve by opening the flesh. U.S. Pat. No. 4,863,469, issued to Van Beek, et al, discloses a nerve tissue expander for lengthening damaged nerve tissue. The apparatus taught in the '469 patent includes a saddle trough attached to an expandable or inflatable plate. The inflatable plate and saddle trough are inserted into the flesh, under the nerve tissue, and the nerve tissue is secured in the saddle trough. The inflatable plate is expanded over a time period thereby lengthening the nerve tissue to overcome any gap that may have occurred in the nerve tissue. This apparatus is bulky and cumbersome and the apparatus must be removed from the body by operative procedure after the nerve tissue has been regenerated.